Of the world’s 43,000 known varieties of spiders, an overwhelming majority are peevish loners: spinning webs, slinging lassos, liquefying prey and attacking trespassers, each spider unto its own.

But about 25 arachnid species have swapped the hermit’s hair shirt for a more sociable and cooperative strategy, in which dozens or hundreds of spiders pool their powers to exploit resources.

And believe it or not, these oddball spider socialites may offer fresh insight into an array of human mysteries: where our personalities come from, why some people can’t open their mouths at a party while others can’t keep theirs shut and, why — no matter our age — we can’t seem to leave high school behind.

“It’s very satisfying to me that the most maligned of organisms may have something to tell us about who we are,” said Jonathan Pruitt, a biologist at the University of Pittsburgh who studies social spiders.

The new work on social spiders is part of the expanding field of animal personality research, which seeks to delineate, quantify and understand the many stylistic differences that have been identified in a vast array of species, including monkeys, minks, bighorn sheep, dumpling squid, zebra finches and spotted hyenas.

Animals have been shown to differ, sometimes hugely, on traits like shyness, boldness, aggressiveness and neophobia, or fear of the new. Among the big questions in the field are where those differences come from and why they exist.

Reporting recently in the Proceedings of the Royal Society B, Pruitt and Kate Laskowski of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin have determined that character-building in social spiders is a communal affair. While they quickly display the first glimmerings of a basic predisposition — a relative tendency toward shyness or boldness, tetchiness or docility — that personality is then powerfully influenced by the other spiders in the group.

In lab experiments, the researchers showed that spiders exposed to the same group day after day developed stronger and more distinctive personalities than those who were shifted from one set of spiders to the next. Moreover, the spiders in a stable social setting grew ever less like one another over time.

In other words, far from fostering behavioral conformity, a predictable social life accentuated each spider’s personal style, rather as the characters in a sitcom — the Goth girl, the huckster, the lovable buffoon — rise ever more to type with every passing laugh-tracked week.

“The longer the spiders were with the same individuals, the stronger their personalities became, and the more different they became from each other,” Pruitt said. “The aggressive ones became much more aggressive, the docile ones more docile.”

The researchers view the development of strong personalities as the behavioral version of so-called niche partitioning, carving out a specialty in a crowded, competitive world.

The concept is most familiarly applied to the study of animal foraging practices. For example, when stickleback fish are feeding in densely populated waters, Laskowski said, “some will specialize on critters in rocks, others on little plankton.”

By adopting distinctive foraging tactics, “you don’t have to fight all the time,” she said. “You have your own little niche.”

For the spiders, behavioral partitioning appears to serve as the foundation of their sociality and hence of their extraordinary success.

The researchers studied Stegodyphus mimosarum, small social spiders that live in colonies of 20 to 300 individuals, weaving huge communal webs the size of automobiles over the trees and bushes of the Kalahari in southern Africa. The spider communities gain their strength through a division of labor, with some members specializing in web repair, some in attacking and subduing prey.

Still others tend to the young, regurgitating liquefied food into an offspring’s mouth and eventually liquefying their own bodies to nourish the next generation. Through team effort and professional expertise, the social spiders thrive.

But how to decide who gets which job? Among social insects like honeybees, caste depends on age; young bees work in the nursery, older bees forage or defend the hive. For ants, what they’re fed as larvae determines whether they are soldiers or workers. For the spiders, personality appears to dictate profession.

Pruitt and his colleagues have determined that the spiders in charge of defending the colony and capturing prey score high on tests of aggression, while those caring for the young are measurably more docile. Yet the process of finding one’s true spider calling is a gradual one and depends on an assessment of the needs of the larger spider society.

Alison Bell, who studies stickleback personality at the University of Illinois, says the spider work illustrates the mix of plasticity and predilection that underlies personality.

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